1. Field of the Invention
This invention is concerned with a new lubricating composition and method for use in main turbines and gears, auxiliary turbine installations, certain hydraulic equipment and for general mechanical lubrication.
The lubrication of turbine engines, particularly those used in environments containing water requires lubricants which exhibit effective rust inhibition both during engine operation and while idle. In addition these lubricants must provide the desired oxidation stability, air release, and extreme pressure/antiwear properties.
The compositions of the invention exhibit excellent vapor space rust protection, improved oxidation stability, extreme pressure/antiwear, and air release properties.
2. State of the Art
The art to which this invention relates already is aware, inter alia, of U.S. Pat. No. 2,775,560. This patent discloses the use of carboxylic acids as vapor space rust inhibitors but indicates that such acids, to give vapor space rust protection, must be activated by oil soluble sulfur-containing compounds, phenolic compounds and/or by aliphatic polycarboxylic acids and their derivatives.
While the compositions claimed in U.S. Pat. No. 2,775,560 reportedly provide vapor phase rust protection, no mention is made that carboxylic acids VSI additives degrade the other critical properties of the lubricating oil. In fact, the other properties (oxidation stability and bearing compatibility) critical for these oils are ignored which implies that the claimed formulations may be deficient in these areas. The addition of only the VSI additive (even in the presence of phenolic and aliphatic polycarboxylic acid compounds as claimed in U.S. Pat. No. 2,775,560) degrades the oil performance in the critical areas. By contrast the present invention discloses a lubricating oil that not only provides vapor space rust protection, but exhibits outstanding liquid rust protection, oxidation stability, bearing compatibility, and air release properties.